Describe, in terms of X-ray photons, the attenuation mechanism of Compton scattering.
A parallel beam of X-rays is incident normally on a composite radiation shield designed for a medical radiography suite. The shield consists of a uniform barium-doped polymer layer between x=0x = 0x=0 and x=1.6 cmx = 1.6\text{ cm}x=1.6 cm, followed by a denser backing layer.
The variation of the intensity I I\,I of the X-rays with depth x x\,x in the shield is shown below.
Use the graph to determine the attenuation coefficient μ \mu\,μ in cm−1\text{cm}^{-1}cm−1 of the barium-doped polymer layer.
Use the graph to determine the exposure time ttt (in seconds) for the total radiant energy incident per cm2\text{cm}^2cm2 at a depth of 1.6 cm to be 5.4 J.
Beyond x=1.6 cmx = 1.6\text{ cm}x=1.6 cm, the polymer is replaced by the denser backing layer. Describe and explain the key features of the gradient and shape of the continuation of the curve of I I\,I versus x x\,x beyond x=1.6 cmx = 1.6\text{ cm}x=1.6 cm compared to a hypothetical continuation of the polymer layer.
